An architecture for high-performance direct conversion radios is disclosed in co-pending U.S. patent application Ser. No. 10/440,026 entitled “CHOPPER-DIRECT-CONVERSION (CDC) RADIO ARCHITECTURE” and filed May 16, 2003, the content of which is incorporated herein by reference. The architecture disclosed employs a phase-alternating mixer (PAM) that outputs a double-sideband (DSB) signal for use throughout the receiver circuitry. Such double-sideband signal paths eliminate the use of baseband frequencies that are generally problematic in large-scale circuit integration. In addition, problems associated with direct-conversion, such as local oscillator (LO) leakages, direct current (DC) offsets, low frequency noise and the like are all eliminated by relocating the local oscillator frequency away from the radio frequency (RF) employed for transmission. In addition, harmonic rejection for such an architecture is disclosed in co-pending U.S. patent application Ser. No. 10/457,825 entitled “HARMONIC REJECTION GATED-SWITCHING MIXER” and filed Jun. 9, 2003, and combined alias and harmonic rejection for such an architecture is disclosed in co-pending U.S. patent application Ser. No. 10/464,424 entitled “PHASE-ALTERNATING MIXER WITH ALIAS AND HARMONIC REJECTION” and filed Jun. 18, 2003, the content of which is incorporated herein by reference.
There is, therefore, a need in the art for a low cost direct conversion mixer implementing a phase alternating mixer function.